Spectral Holeburning and Four-Wave Mixing in InGaAs/InP Quantum Wells
Excitons in III-V quantum well structures have been given rise to a broad variety of new physics  and device applications . The linear optical properties of the excitons have been exploited to study effects of reduced dimensionality and of materials properties  while the nonlinear properties form the basis for a potential new family of switching devices . The lowest energy heavy hole exciton is of most interest central issue for the understanding of new physical phenomena and new devices is the nature of the interaction of the exciton with its static and dynamic environment. Interface roughness leads to inhomogeneous broadening of the exciton energy which can be observed in absorption and luminescence . The roughness affects the in-plane localisation properties of the exciton . The interaction of the exciton with acoustic phonons is in turn strongly determined by the localisation properties . A proper understanding of the factors governing localisation is consequently necessary. To date, GaAs/GaA1As quantum wells grown epitaxially have shown both localised and delocalised excitons at low temperature  while especially high quality samples have shown delocalised excitons only . The scenario where all excitons are localised has only recently been observed in III-V quantum wells . In this paper we describe in detail how complete localisation can be achieved in the structure InGaAs/InP. The additional disorder causing localisation is introduced by alloying the well. At the same time inelastic scattering leading to spectral diffusion is considerably enhanced over GaAs quantum wells. The exciton dynamics are measured using spectral holeburning and time-resolved four wave-mixing.
KeywordsRandom Potential Interface Roughness Spectral Diffusion Localise Exciton Linear Optical Property
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